Both types of guitar have something going for them. The narrow neck of the steel-strung guitar allows the thumb to take a greater part in the left-hand fingering, as remarked above about Gary Davis, and also Leo Kottke. If you want to use a lot of different tunings, steel strings respond more rapidly and are more amenable to re-tuning. But the sound difference is in the harmonic response; steel strings generate twice as many harmonics agasinst nylon strings. This results in a "fuller sound" in contrast to nylon, making it harder to play some pieces where, with a nylon string guitar, the notes are distinct when picked. My advice is that, if you've got rid of the classic, get a Martin 0-16NY, which is designed for nylon strings but can be played with light steel or silk'n'steel strings; that way, if you regret the decision, you've got something that you can play either way.